The synthesis of transcobalamin II, a vitamin B12 transport protein, by stimulated mouse peritoneal macrophages.

The concentration of transcobalamin II (TCII), the vitamin B12 binding protein which delivers vitamin B12 to the tissues, was determined in stimulated and non stimulated mouse peritoneal exudate cells (PEC). Following a single intraperitoneal thioglycollate injection there was a marked increase in TCII which was shown to be produced by the adherent cells of the PEC i.e. the macrophages. It has been concluded that the PEC macrophages synthesize TCII.